Signal level and phase control



' May 11, 1948. w. H. SAYER SIGNAL LEVEL AND PHASE CONTROL Filed April 30 1943 4 INVENTOR.

HTTORNEY Patented May 11, 1948 UNITED STATE 5 PATENT OFFICE SIGNAL LEVEL AND PHAS CONTROL William H. Sayer, Passaic, N, J., asslgnor to Allen B. Du Mont Laboratories,

Inc., Passaic, N. J., a

corporation of Delaware Application April 30, 1943, Serial No. 485,224

1 Claim. (Cl. 118-44) which is grounded preferably at its middle point and is provided with an adjustable contact at diiferent points from zero potential to the maximum positive and. negative potentials.

The invention will be understood from the descriptlon in connection with the accompanying drawing, in which the figure is a diagram or connections showing an embodiment of the invention.

In the drawing, reference character I indicates a vacuum tube to the grid 2 of which a signal is applied from the input terminal 3. The usual coupling condenser 4 and grid leak 5 are shown. Podtive potential is applied to the plate 6 through resistance] and the cathode 8 is blasedby resistance 9.

A resistance It is grounded at its midpoint II and the opposite ends thereof are coupled by co densers l2 and I3 to the plate 6 and cathode 8, respectively, thus constituting a potentiometer having a point at zero potential. 4 A sliding contact I5 is movable along the potentiometer ll so zero potential as well as any desired positive and negative potentials can be taken 01! through resistance It to grid l'l bf gas illled triode l8 having an adjustable resistance It in its plate circuit and having a cathode 2| biased by resistance 2!. A number of condensers "of different sizes are adapted to be selectively conected between the plate II and cathode II by switch II so that the time constant of discharge of tube ll can besuitably adjusted so as to ob tain sawtooth waves of the desired frequencies attbcoutputlllntheknownway.

The operation is as follows:

The synchronizing signal from any convenient source, not shown, is connected to the terminal 3 and fed to the grid 2 of amplifier tube l. The plate load resistance 1 and cathode load or biasing resistance 9 of tube l are equal. The potentiometer III that has its ends capacitatively coupled to the plate 5 and cathode 8, respectively,

has its center grounded so that by adjustment of the contact I5 a gain control for either phase of the signal is made available so that the sawtooth sweep generating device to which it is connected can always be triggered by a positive signal whether a positive or negative signal is fed to the amplifier for the synchronizing signal.

What-is claimed is:

A device for varying the amplitude and controlling the polarity of an electrical. signal, which comprises a vacuum tube havingequal resistors respectively in series with its plate and cathode,

said plate resistor being connected to a source of positive potential and said cathode being connected to ground, a potentiometer grounded intermediate its ends, a condenser coupling one end of said potentiometer to said plate, a condenser of the same size coupling the other end of said potentiometer to said cathode and a sliding contact for said resistor adapted to be moved along said potentiometer onto and along opposite sides of its grounded point.

/ WILLIAM H. SAYER.

REFERENCES crrnn UNITED STATES PATENTS 1 Number. Name Date 1,933,219 Nakajima et a1 Oct. 31, 1933 2,118,977 Lewis et al. May 31, 1938 2,165,770 -Tolson June 11, 1939 2,271,876 Seeley Feb. 3, 1942 Keck et al. July 18, 1941' 

